Radial wire bonder and selectable side view inspection system

ABSTRACT

A wire bonding machine has a wire bonding head that provides five directions of movement or degrees of freedom. The radial direction of movement supports the wire bonding process and reduces the moving mass of the wire bonder during the generation of the wire bonds. The wire bonding machine further includes a selectable side view inspection system. Through a group of optical components, the assembly process can be selectively viewed from either a side view or a top view. The side view of the assembly process provides for improved analysis of the wire bond quality which can be monitored by a camera.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to semiconductor device manufacturing,and more particularly, to wire bonding machines.

2. Description of the Prior Art

In manufacturing a semiconductor device, such as an semiconductor device110 as illustrated in FIG. 1A, packaging is often required so that thesignals can be bidirectionally communicated between the semiconductordevice and other electronic devices. Semiconductor device 110 includes asemiconductor die or substrate 112 inserted or molded into a package 114so that the semiconductor device may be installed onto a printed circuitboard (not illustrated). The package 114 further provides a metalleadframe 116 so that electrical signals may be communicated between thesemiconductor die 112 and the printed circuit board and other integratedcircuits 110 or electronic components.

Referring to FIG. 1A, the semiconductor device 110 includes the dualinline pin package 114, the semiconductor die 112, the metal leadframe116, a molded compound shell 118, and bond wires 120. The bond wires 120are made of a conducting material, preferably gold or aluminum, andcouple to the semiconductor die 112 at one end and the leadframe 116 atthe opposite end. The traces of the lead frame that couple to theprinted circuit board are often referred to as pins 122.

In the semiconductor device manufacturing process a wire bonding machine(not illustrated in FIG. 1A) couples the bond wires 120 to thesemiconductor die 112 and the leadframe 116. Referring to FIG. 1B, abonding tool 124 of the wire bonding machine generates a ball bond 126between the bond wire 120 and the semiconductor die 112. The bondingtool 124 is coupled to a bonding head (not illustrated in FIG. 1B) ofthe wire bonding machine. Referring to FIG. 1C, the bonding tool 124 hascompleted a wedge bond 128 between the bond wire 120 and the leadframe116.

Generally thermosonic bonding techniques of bonding may be used togenerate the ball bond 126. Thermosonic bonding utilizes a heat sourceto heat one end of the bond wire 120 to generate a ball andsimultaneously applies a vertical load to the ball while ultrasonicallyexciting the bond wire 120. Generally ultrasonic bonding techniques areused to generate the wedge bond 128. In generating the wedge bond, thebond wire 120 is first wedged between the leadframe 116 or other bondingsurface and the bonding tool 124 as illustrated in FIG. 1B. While thebond wire 120 is under a vertical load, a mechanical motion or pulsingof the bonding tool 124 generates an ultrasonic wave motion generatingsufficient energy to heat the end of the bond wire 120 breaking surfaceoxides on the bonding surface and at the end of the bond wire so thatthe new surfaces may cold-weld together. Proper loading and ultrasonicwave motion must occur for the wedge bond 128 to be properly formed.

The bonding of the bond wire 120 in FIG. 1C is referred to as ball-wedgebonding. In the case where a wedge bond 128 is formed at both ends ofthe bond wire 120, it is referred to as wedge-wedge bonding. FIG. 1Dillustrates wedge-wedge bonding of the bond wire 120. A wedge bond 128is formed at the end of the bond wire 120 attached to the semiconductordie 112 and a second wedge bond 128 is formed at the end of the bondwire 120 attached to the leadframe 116. Wedge-wedge bonding may bepreferable such that thermosonic bonding techniques of ball bonding maybe avoided. In ball-wedge bonding the bonding tool 124 may be acapillary device. In wedge-wedge bonding the bonding tool 124 may be awedge device.

Referring to FIG. 1E, the semiconductor device 110 includes thesemiconductor die 112 and the leadframe 116. FIG. 1E illustratesball-wedge bonding. The semiconductor die 112 includes bonding pads 130so that the bonding wires 120 may be attached thereto using ball bonds126. The surface of the bonding pads 130 are made of a conductivematerial which is preferably aluminum metal. The leadframe 116 includescontact points 132 such that the bonding wires 120 may be attachedthereto using wedge bonds 128. FIG. 1F illustrates wedge-wedge bonding.The bonding wires 120 are attached to the bonding pads 130 of thesemiconductor die 112 using wedge bonds 128. The bonding wires 120 areattached to the contact points 132 of the lead frame 116 using wedgebonds 128.

In order to bond to all bonding pads 130 of the semiconductor die 112and to all the contact points 132 on the leadframe 116, the bonding tool124 must be properly positioned. Previously the proper position of thebonding tool was accomplished by physically moving the bonding tool 124itself from one point to another point while the semiconductor deviceremained fixed, physically moving the semiconductor device 110 while thebonding tool 124 remained fixed, or moving both the bonding tool 124 andthe semiconductor device 110. Furthermore in wedge-wedge bonding, thebond wire connection path must be aligned with the wire feedingdirection of the bonding tool.

Previously automatic wedge wire bonders provided four axis of motionnamely X, Y, Z, and θ (theta) to perform wire bonding. The X and Y axismovements position the semiconductor bonding pads 130 of thesemiconductor die 112 under the bonding tool 124 or position the contactpoints 132 of the leadframe 116 to be under the bonding tool 124.Traditionally, the X and Y axis movements further define the locus ofthe wire path from the bonding pad 130 to the contact point 132. The θrotational axis of movement aligns the wire feed direction of thebonding tool 124 with the wire path. Referring to FIG. 1C, the Zvertical axis of movement provides that the bonding tool 124 with itswedge makes contact with the bond wire 120 which in turn makes contactwith the bonding pads 130 or contact points 132 such that the weldingprocess may occur.

In order to perform the wire bonding process previous wire bonders maymove the semiconductor device 110 or the bonding head coupled to thebonding tool 124 in various ways. In one case the semiconductor device110 is moved in the X, Y, and θ axis while the bonding head and bondingtool 124 are moved only in the Z axis. In another case the semiconductordevice 110 is moved in the X and Y axis while the bonding head andbonding tool 124 are moved in the θ axis and the Z axis. In another casethe semiconductor device 110 is moved only in the θ axis while thebonding head and bonding tool 124 are moved in the X, Y, and Z axis. Inanother case the semiconductor device 110 is moved only in the Z axiswhile the bonding head and bonding tool 124 are moved in the X, Y, and θaxis. In another case the semiconductor device 110 is moved in the Z andθ axis while the bonding head and bonding tool 124 are moved in the Xand Y axis. In another case the semiconductor device 110 is stationaryduring the bonding process while the bonding head and bonding tool 124are moved in the X, Y, θ, and Z axis.

In order to increase the efficiency of the wire bonding process, it isdesirable to handle the semiconductor devices using an automaticcontinuous indexing technique. Automatic continuous indexing is atechnique where an index mark on the semiconductor device 110 or adevice carrier (not illustrated) is used to automatically align abonding start point as the next semiconductor device is inserted intothe wire bonder for bonding. Wire bonding machines that move thesemiconductor device 110 in order to position it under the bonding tool124, can hardly use an automatic continuous index handling method. It isdesirable to provide automatic continuous index handling such that thesemiconductor devices 110 are stationary during the bonding process.

Semiconductor devices 110 of today may be much larger and may require alarge number of pins 122 in order to communicate properly with a printedcircuit board. These large devices have a relatively large mass andgenerally require a heavy workholder clamp in order to hold thesemiconductor device 110 in the bonding machine. In wire bonders such asthese where the semiconductor device 110 is moved, the large mass of theworkholder clamp and the large semiconductor devices 110 result in poordynamic stability and vibrations during a high speed bonding process. Aprior technique used to combat the vibration problems in wire bondersreduces the bonding speed such that proper dynamic stability may beachieved. However, it is desirable to operate wire bonding machines attheir maximum bonding speed when bonding large devices. It is alsodesirable to keep the semiconductor device 110 stationary during thewire bonding process.

In wire bonders where the semiconductor device 110 is stationary whilethe bonding head and bonding tool 124 are moved in the X, Y, θ, and Zaxis, the bonding head is rather complicated and has a relatively largemass. The large mass of the bonding head makes it difficult to achievegood dynamic stability. This is particularly a problem when the bondinghead and bonding tool 124 move in the X and Y axis directions from thesemiconductor device bonding pad 130 to the contact points 132 asillustrated by the arrow 142 in FIG. 1E and FIG. 1F. A prior techniqueused to provide proper dynamic stability is to reduce the speed of thebonding process. However, it is desirable to speed up the bondingprocess of semiconductor devices in order to increase the throughput andthereby lowering manufacturing costs.

In the wire bonding process it is desirable to occasionally view theprogress of the wire bonder in order to maintain quality controls.Traditionally a microscope (not illustrated) is used to visualize thereal time wire-bonding process. The microscope may be coupled to thebonder and aligned such that its lens points to the device to allowvisual inspection of the top surface of semiconductor die 112 andleadframe 116. In wire bonders where the bonding head and bonding tool124 move and rotate in various directions it is difficult if notimpossible to properly view the wire bonding process. However, it isdesirable to properly view the bonding process in the case where thebonding head and bonding tool 124 move in order to complete the bondingprocess.

SUMMARY OF THE INVENTION

It is an object of the present invention to keep the device beingassembled under a bonding head stationary while performing a wirebonding process.

Another object of the present invention is to provide a 10 radial axisof motion for the wire bonding process.

A still further object of the present invention is to provide aselectable side view inspection system.

Briefly, a preferred embodiment of the present invention includes a wirebonding machine having a wire bonding head that provides five directionsof movement or degrees of freedom. The radial direction of movementsupports the wire bonding process and reduces the moving mass of thewire bonder during the generation of the wire bonds. A selectable sideview inspection system may be included. Through a group of opticalcomponents, the assembly process can be selectively viewed from either aside view or a top view. The side view of the assembly process may beselectively monitored by a camera which may be also selected to view thetop view.

An advantage of the present invention is that the wire bonding processcan be performed at an increased rate of speed and continue to supportautomatic handling systems.

Another advantage of the present invention is that the moving mass ofthe wire bonder during the wire bonding process is reduced therebyimproving the dynamic stability.

A further advantage of the present invention is that the quality of awire bond can be better analyzed during the actual wire bonding process.

These and other objects and advantages of the present invention will nodoubt become obvious to those of ordinary skill in the art after havingread the following detailed description of the preferred embodimentswhich are illustrated in the various drawing figures.

IN THE DRAWINGS

FIG. 1A is a cutaway view of a prior art dual inline pin plasticintegrated circuit package;

FIG. 1B is a magnified cross sectional side view of a bonding toolgenerating a prior art ball-wedge bond;

FIG. 1C is a magnified cross sectional side view of a completed priorart ball-wedge bond;

FIG. 1D is a magnified cross sectional side view of a completed priorart wedge-wedge bond;

FIG. 1E is a magnified top view of a prior art semiconductor die andpackage leadframe illustrating the wire bonding process of prior artball-wedge wire bonders;

FIG. 1F is a magnified top view of a prior art semiconductor die andpackage leadframe illustrating the wire bonding process of prior artwedge-wedge wire bonders;

FIG. 2 is a magnified top view of a semiconductor die and packageleadframe illustrating the wire bonding process of the presentinvention;

FIG. 3 is a frontal view a wire bonding machine of the presentinvention;

FIG. 4 is a cross sectional side view of the wire bonding machine ofFIG. 3;

FIG. 5 is a magnified frontal view of the bonding head of FIG. 3;

FIG. 6 is a cross sectional side view of the bonding head of FIG. 5; and

FIG. 7 is a schematic drawing illustrating a side-view inspection systemof the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A first embodiment of the present invention includes a bonding head of awire bonding machine having an additional axis of motion. A secondembodiment of the present invention includes a side viewing opticalsystem for viewing in real time the wire bonding process of a wirebonding machine.

Referring to FIG. 2, the first embodiment of the present inventionprovides a radial axis or direction of movement R in the bonding headfrom a fixed X axis and Y axis position. The radial axis is along thebonding path from the bonding pad 130 of the semiconductor die 112 tothe contact point 132 such as illustrated by an arrow 204. The bondinghead provides that the bonding tool 124 or other bonding instruments canmove radially from the bonding pad 130 to the contact points 132 of theleadframe 116 along the radial axis R.

Referring to FIG. 3 and FIG. 4, the wire bonder of the present inventionis referred to herein by the general reference character 300. Wirebonder 300 is preferably a wedge type wire bonder and provides for fivedirectional movements. Wire bonder 300 includes a bonding head 302 thatmoves in five directions X, Y, θ, Z, and radial R. The bonding head 302is supported above the semiconductor device 110 (not illustrated in FIG.3) by a bonding head stand 304. Coupled to the bonding head stand 304 isan X-Y table base 306 having X-direction table linear guides 308 atopposite ends.

Referring to FIG. 4, the X-Y table base 306 has a pair of X-directiontable linear guides 308 at opposite ends. An X-direction table plate310, having nearly matching linear guides 308, is supported by the X-Ytable base 306 at the X-direction table linear guides 308. TheX-direction table linear guides 308 allow the X-direction table plate310 to slide on the X-Y table base 306 along the X axis. Referring toFIG. 3, motion of the X-direction table plate 310 over the X-Y tablebase 306 is provided by an X-direction actuator 311. The X-directionactuator may include a voice coil 312 and an X-direction linear motorassembly 314. The X-direction linear motor assembly 314 is coupled tothe X-Y table base 306 while the voice coil 312 is coupled to theX-direction table plate 310. A force generated between the voice coil312 and the linear motor assembly 314 moves the table plate 310 over thetable base 306. Motion of the X-direction table plate 310 over the X-Ytable base 306 is recorded by an X-direction linear encoder 315 in orderthat a desired X coordinate position may be achieved.

Referring to FIG. 3, the X-direction table plate 310 includes a pair ofY-direction table linear guides 316 at opposite ends. A Y-directiontable plate 318, having nearly matching linear guides 316, is supportedby the X-direction table plate 310 at the Y-direction table linearguides 316. Referring to FIG. 4, the Y-direction table linear guides 316allow the Y-direction table plate 318 to slide on the X-direction tableplate 310 in the Y direction. Motion of the Y-direction table plate 318over the X-direction table plate 310 is provided by a Y-directionactuator 319. The Y-direction actuator 319 may include a Y-directionvoice coil 320 and a Y-direction linear motor assembly 322. TheY-direction linear motor assembly is coupled to the X-Y table base 306while the Y-direction voice coil 320 is coupled to the Y-direction tableplate 318. A force generated between the voice coil 320 and the motorassembly 322 moves the Y-direction table plate 318 over the X-directiontable plate 310. The Y-direction voice coil 320 allows for movement ofthe Y-table plate 318 in the X direction such that it can move freelyover the range of X and Y axis movement. In this manner the Y-directionlinear motor assembly 322 can be stationarily coupled to the X-Y tablebase 306. Referring to FIG. 3, motion of the Y-direction table plate 318over the X-direction table plate 310 is recorded by a Y-direction linearencoder 324 in order that a desired Y coordinate position may beachieved. The linear encoder 324 is coupled to a Y-encoder bracket 326which is coupled to the X-direction table plate 310.

Referring to FIG. 3, a theta actuator 327 rotates the bonding head 302to the proper angular θ direction. The theta actuator 327 may include atheta motor 328 having a theta drive pulley 330. The theta motor 328 iscoupled to a theta motor stand 332 which is in turn coupled to theY-direction table plate 318. The theta drive pulley 330 is coupled to anoutput shaft of the theta motor 328. The theta drive pulley 330 iscoupled to a theta belt 334 which is in turn coupled to a theta inputpulley 336. Referring to FIG. 4, the theta input pulley 336 is couplednear a top end of a theta input shaft 338. A lower end of the thetainput shaft 338 is coupled to a gearing system 340 which is in turncoupled to an end of a main shaft 342. Coupled at an opposite end of themain shaft 342 is a turning plate 343 of the bonding head 302. Thegearing system 340 provides a selective reduction in the angularmovement from the theta input shaft 338 to the main shaft 342. Referringto FIGS. 3 and 4, the theta input shaft 338 is surrounded by an inputshaft side bearing 344 which is encased by an input shaft bearinghousing 346. The gearing system 340 is partially encased by a gearinghousing 348. Referring to FIG. 4, the main shaft 342 is surrounded by amain shaft bearing 350 which is in turn encased by a main shaft bearinghousing 352. The input shaft side bearing 344 and the main shaft bearing350 allow rotational movement respectively in the input shaft 338 andthe main shaft 342. The input shaft bearing housing 346 is coupled tothe gearing housing 348 which is in turn coupled to the Y-directiontable plate 318. The main shaft bearing housing 352 is coupled to theY-direction table plate 318 to support the main shaft 342 in an axialposition.

The turning plate 343 coupled to the end of the main shaft 342 supportsthe bonding head 302 above the semiconductor device 110 (not illustratedin FIGS. 3, 4, 5, and 6). As illustrated in FIGS. 3 and 4, the wirebonder 300 may include a coaxial optical assembly 353 for viewing thebonding operation in real time. As illustrated in FIG. 7, the coaxialoptical assembly 353 is supported by an optics stand 402 which is inturn coupled at its base to the Y-direction table plate 318. The coaxialoptical assembly 353 includes a penta prism 403, a lens system 404, anda camera 405. The wire bonder 300 further includes a bonding head cablehousing 354 that encases a flat cable 412 which may be similar to aribbon type cable having a multiple of conductors for signal, power, andground lines. The cable 412 carries the appropriate signals to operatethe bonding head 302. The flat cable 412 may be wrapped around a cablespool 414 which is coupled to the turning plate 343. The bonding headcable housing 354 is coupled to the main shaft bearing housing 352.Referring to FIGS. 5 and 6, a bonding head support bracket 502 iscoupled to the turning plate 343. The bonding head support bracketincludes a pair of Z-direction linear guides 504 vertically positioned.

A Z-sliding plate 506, having nearly matching linear guides 504, issupported by the bonding head support bracket 502 at the Z-directionlinear guides 504. The Z-direction linear guides 504 allow the Z-slidingplate 506 to vertically slide against the bonding head support bracket502 in the Z direction. Referring to FIG. 5, motion of the Z-slidingplate 506 against the bonding head support bracket 502 is provided by aZ-direction actuator 507. The Z-direction actuator 507 may include aZ-direction voice coil 508 and a Z-direction linear motor assembly 510.The Z-direction linear motor assembly 510 is coupled to the bonding headsupport bracket 502 while the Z-direction voice coil 508 is coupled tothe Z-sliding plate 506. A force generated between the voice coil 508and the motor assembly 510 moves the Z-sliding plate 506 verticallywhile the bonding head support bracket 502 remains vertically fixed. Asshown in FIGS. 5 and 6, the vertical motion of the Z-sliding plate 506is recorded by a Z-direction linear encoder 512 in order that a desiredZ coordinate position may be achieved. The linear encoder 512 is coupledto a Z-direction encoder bracket 514 which is in turn coupled to theturning plate 343. Referring to FIG. 5, the Z-sliding plate 506 includesa pair of radial direction linear guides 516 horizontally coupledrespectively near a top and lower edge of the plate 506.

A bonding head subassembly 518, having nearly matching linear guides516, is supported by the Z-sliding plate 506 at the radial directionlinear guides 516. The radial direction linear guides 516 allow thebonding head subassembly 518 to horizontally slide against the Z-slidingplate 506 such that it slides in a radial direction R. Motion of thebonding head subassembly 518 against the Z-sliding plate 506 is providedby a radial-direction actuator 519. The radial-direction actuator 519may include a horizontally mounted radial-direction voice coil 520 and aradial-direction linear motor assembly 522. The radial-direction linearmotor assembly 522 is coupled to the turning plate 343 while theradial-direction voice coil 520 is coupled to the bonding headsubassembly 518. A force generated between the voice coil 520 and themotor assembly 522 moves the bonding head subassembly 518 horizontallyagainst the Z-sliding plate 506. Additionally, the radial-directionvoice coil 520 allows for movement of the bonding head subassembly 518in the Z direction axis such that it can move freely over the range of Zand radial axis movement. In this manner the radial-direction linearmotor assembly 522 can be stationarily coupled to the turning plate 343.Referring to FIG. 6, motion of the bonding head subassembly 518 againstthe Z-sliding plate 506 in the radial direction R is recorded by aradial-direction linear encoder 602 in order that proper radialpositions may be achieved. The radial motion of the bonding headsubassembly 506 further improves the wire bonding process. The linearencoder 602 is coupled to a radial-direction encoder bracket 604 whichis coupled to the Z-sliding plate 506.

In order to perform the wire bonding operation the bonding headsubassembly 518 includes bonding instruments such as a wire clamp 606and a transducer 608. In order to perform wedge bonding the bonding headsubassembly 518 includes a bonding wedge 610. The bonding wedge 610 andthe wire clamp 606 provide similar capability as the bonding tool 124but do not perform ball bonding. Other devices may be connected to thebonding head subassembly 518 in order to perform a different wirebonding technique or other steps in an assembly process for electricaldevices.

The wire bonder 300 utilizes the X-direction actuator 311 and theY-direction actuator 319 to position the bonding wedge 610 over abonding pad 130. The theta actuator 327 rotates the bonding headsubassembly 518 so that the wire path is aligned with the wire feedingdirection from the wire clamp 606. In this manner the bonding wedge 610is also aligned with the wire path. The radial-direction actuator 519 isoperated to. move the bonding head subassembly 518 to its home orinitialization position. The Z-direction actuator 507 moves the bondinghead subassembly 518 downward towards the bonding pad 130 to effectuatea bond. The bonding instruments such as the bonding wedge 610, wireclamp 606, and transducer 608 complete the bond of the wire 120 at oneend. The Z-direction actuator 507 moves the bonding head subassembly 518upward and away from the completed bond at the bonding pad 130. Theradial-direction actuator 519 moves the bonding head subassembly 518 onthe radial path 204 to a point above the contact point 132 of theleadframe 116. The Z-direction actuator 507 moves the bonding headsubassembly 518 downward towards the contact point 132 to effectuate abond. The bonding instruments such as the bonding wedge 610, wire clamp606, and transducer 608 complete the bond of the wire 120 at the secondend and cuts the wire 120. Then the Z-direction actuator 507 moves thebonding head subassembly 518 upward and away from the completed bond atthe contact point 132 of the leadframe 116. The foregoing sequence ofsteps are repeated to effectuate wire bonds to the desired bonding pads130 and contact points 132.

Because the wire bonder 300 has the bonding head 302 perform all motionsof the assembly process while the semiconductor device 110 remainsstationary, the space underneath may be utilized for transporting thedevice 110 after completion of the assembly process. Additionallybecause the bonding head 302 performs all motions of the assemblyprocess, the mass and inertia during the wire bonding process areconstant such that the size of the device 110 is irrelevant in how fasta bonding head 302 may move. Because the bonding head subassembly 518moves along the radial axis R, the bonding head 302 does not need tomove along the wire path. The radial axis movement decreases the timerequired to make a bond. Thus the movement of the bonding head 302 inthe X-Y direction is less important and may be slowed to improve dynamicstability.

Referring to FIGS. 6 and 7, a selectable side view inspection system isprovided. Providing a side view of the wire bonding process allows anoperator to further examine the quality of the wire bonds. An operatorcan determine if the Z-direction actuator 507 is properly positioningthe bonding head subassembly 518 for bonding. The operator can furtherexamine if the bonding instruments are operating properly, particularlythe transducer 608. Examining the side view of the wire bond provides anopportunity to automate the quality control process by feeding the sideview to a computerized inspection system. The selectable side viewinspection system may also be adapted to other assembly processesparticularly in the assembly of other electronic components or systems.

The major optical components of the side view inspection system includethe coaxial optical assembly 353, a central mirror 616, a side view lens618, and a side view mirror 620. Side view mirror 620 being tilted at anangle of sixty-seven and one-half degrees from the horizontal plane,views the object that is being assembled, such as the semiconductordevice 110, at a forty-five degree angle. The light received by the sideview mirror 620 is reflected horizontally through the side view lens 618and to the central mirror 616. Central mirror 616 being tilted at anangle of forty five degrees from a horizontal plane, reflects the lightreceived through the side view lens 618 at a right angle verticallytowards the penta prism 403. The side view lens 618 may movehorizontally along the ray reflected light in order to properly focusthe image. The light directed towards the camera 405 is bent at a ninetydegree angle from the vertical plane through the penta prism 403 andfocused by the lens system 404. In this manner a side view of an objectthat is near the assembly instruments such as the bonding wedge 610 maybe provided. If central mirror 616 is allowed to horizontally move outof the vertical line of sight of the penta prism 403, the coaxialvertical view may be received by the camera.

The optical components of the side view inspection system may be coupledto an assembly machine such as the wire bonder 300. Referring to FIG. 6,side view lens 618 is coupled to a lens holder 622. The side view lens618 and lens holder 622 are encased within a side view inspection lensand mirror housing 624. The lens 618 and holder 622 may slide within thelens and mirror housing 624 in order to adjust the focus of the image.The lens and mirror housing 624 is coupled to a side inspection housingbracket 626 which in turn is coupled to the turning plate 343. The sideview mirror 620 is coupled to one side of the lens and mirror housing624.

Central mirror 616 is coupled to a mirror holder 628 having a forty-fivedegree inclination with the horizon. Mirror holder 628 is coupled to arack 630. A linear guide holder 632 and a motor bracket 634 are coupledto the turning plate 343. A linear motion guide 636 is coupled to thelinear guide holder 632. The mirror holder 628 is supported by thelinear motion guide 636 such that the holder 628 may horizontally slideagainst the linear motion guide 636. A gear motor 638 is coupled to themotor bracket 634 in order to provide motion for the central mirror 616.A pinion gear (not illustrated) is coupled to an output shaft of thegear motor 638. The pinion gear of the gear motor 638 linearly drivesthe rack 630 such that the central mirror 616 moves in a horizontalfashion.

The horizontal movement in the central mirror 616 selects whether a topview or a side view is selected. A top view image would appear somewhatsimilar to the illustration depicted in FIG. 2. A side view image wouldappear somewhat similar to the illustration depicted in FIGS. 1B and 1C.If a top view (also referred to as a coaxial view or vertical view) ofthe device under assembly is desired, the central mirror 616 ishorizontally moved out of the vertical line of sight. If a side view isdesired, the central mirror 616 is moved horizontally to a properposition in order to reflect the received light. In this manner onecamera is utilized to provide two different views of the object that isundergoing assembly. Because the side view optics are mounted to thebonding head 302, the side view image provided moves and rotates withthe bonding head 302. Thus a side view may be provided in any X or Yposition and any θ orientation.

Although the present invention has been described in terms of thepresently preferred embodiments, it is to be understood that suchdisclosure is not to be interpreted as limiting. Various alterations andmodifications will no doubt become apparent to those skilled in the artafter having read the above disclosure. Accordingly, it is intended thatthe appended claims be interpreted as covering all alterations andmodifications as fall within the true spirit and scope of the invention.

What is claimed is:
 1. A method of radial wire bonding, the stepscomprising:moving a bonding instrument (606, 608, or 610) in an X and aY direction over a bonding pad (130) in response to an X-directionactuator (311) and a Y-direction actuator (319); turning said bondinginstrument (606, 608, or 610) to align with a path between a bonding pad(130) and a contact point (132) in response to a theta actuator (327);lowering said bonding instrument (606, 608, or 610) onto said bondingpad (130) in response to a Z-direction actuator (507); generating afirst wire bond between one end of a bond wire (120) and said bondingpad (130) with said bonding instrument (606, 608, or 610); raising saidbonding instrument (606, 608, or 610) above said bonding pad (130) inresponse to said Z-direction actuator (507); moving said bondinginstrument (606, 608, or 610) and routing said bond wire (120) along aradial path from said bonding pad (130) to a contact point (132) inresponse to a radial-direction actuator (519); lowering said bondinginstrument (606, 608, or 610) onto said contact point (132) in responseto said Z-direction actuator (507); generating a second wire bondbetween an opposite end of said bond wire (120) and said contact point(132) and cutting said bond wire (120) at said opposite end with saidbonding instrument (606, 608, or 610); and raising said bondinginstrument (606, 608, or 610) above said contact point (132) in responseto said Z-direction actuator (507).